Simon Effect
The finding that reaction times are usually faster, and reactions are usually more accurate, when the stimulus occurs in the same relative location as the response, even if the stimulus location is irrelevant to the task.
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Origin
Named for J. Richard Simon (1929–2017), an American psychologist at the University of Iowa, who first reported the phenomenon in a 1967 paper with Alan Rudell in the Journal of Applied Psychology. His follow-up 1969 paper in the Journal of Experimental Psychology established the visual version that became the standard paradigm.
Updated February 22, 2026